A frameless door, such as commonly provided on convertible motor vehicles can be more susceptible to wind noise than a framed door. More particularly, without the structural door frame to provide support to the window, the window/door glass G may be pulled outboard off of the weather seals S by aerodynamic lifting forces on the glass at higher vehicle speeds (note action arrow A in FIG. 1a).
In order to mitigate this design weakness, it is common to provide a U-shaped seal retainer R which restrains the window glass G from deflecting outboard and losing contact with the seal S thereby limiting the occurrence of noise. The greater the penetration of the top edge E of the window glass G into the seal S, the greater the reduction in wind noise.
When the window glass G is located within the U-shaped seal retainer R, the top edge E of the glass G will impact the seal retainer R if the door swings open in the direction of action arrow B. In order to protect the window glass G and prevent this from happening, these types a frameless glass window operating systems invariably incorporate some form of “glass-index” function in which a window regulator is designed to drop the window by a small amount whenever the door is opened in order to create clearance between the top edge E of the window glass G and the seal retainer R (note action arrow C in drawing FIG. 1b).
FIG. 2 illustrates a prior art frameless-door glass window operating system wherein the operator manipulates the door handle DH to release the door latch DL and begin opening the door. The door motion is detected by an ajar switch AS which then sends a signal along the line L to the window regulator WR. In response to that signal, the window regulator WR displaces the window glass G down to the indexed position necessary to provide clearance of the seal retainer for opening the door (see FIG. 1b and note edge E of window glass G positioned lower than end M of retainer R). It should be appreciated that in this prior art frameless-door window operating system, the indexing function is not initiated until the door is already partially opened. Thus, the prior art system is susceptible to the edge E of the window glass G “clipping” the U-shaped retainer R if the vehicle operator opens the door quickly.
This document relates to a new and improved frameless-door glass window operating system that ensures that the window is properly indexed to clear the seal retainer R simultaneously and, more preferably, before the door is unlatched. This virtually eliminates any, possibility of the edge E of the window glass G clipping the retainer R since the window is indexed before the door is opened.